1. Field of the Invention
The present invention relates to a power control device, more particularly, to a power control device capable of operating an electronic device at a low voltage state by controlling a power supply in accordance with an input voltage.
2. Description of the Related Art
A typical example of an electronic device is a video display device such as TV and monitor.
In general, an operational voltage range of a video display device is different in compliance with voltage standard by nations. In other words, an image display device normally operates above about 80V in the areas of the US and Japan of a 110V voltage standard, and the video display device operates above about 180V in the areas of Korea and European countries of a 220V voltage standard.
However, recently, the electronic devices are designed to use both voltages of 110V and 220V. Therefore, the electronic devices operate above about 80V.
A power control device of a general video display device will be described with reference to the accompanying drawings.
FIG. 1 is a schematic of a related power control device.
As shown in FIG. 1, a related power control device comprises: a power input portion 10 for supplying a power; a rectifier 20 for rectifying and smoothing a power supplied through the power input portion 10; a power control unit 30 receiving a rectified and smoothed voltage by the rectifier 20 to control a power; and a transformer 40 receiving a rectified and smoothed voltage by the rectifier 20 to emit a power supplied to the first side into the second side in accordance with a control of the power control unit 30.
Here, the rectifier 20 includes a rectifying diode BD rectifying an input power through the power input portion 10 and a capacitor C1 for smoothing the rectified voltage through the rectified diode BD.
In addition, the one end of the switching transformer 40 is connected to the output terminal of the rectifier 20, and the other end is connected to the power control unit 30 to include a resistor R for supplying a rectified and smoothed voltage to the power control unit 30 through the rectifier 20.
The related power control device having the above structure operates as follows;
The power is received from the power input portion 10, and it is rectified through the rectifying diode BD regardless of the main(+)/sub(−) periods of a voltage input. The rectified voltage goes through the power input portion 10, and it is charged and switched in the capacitor C1.
In addition, a rectified and smoothed voltage is provided to the power control unit 30 through the resistor R.
A rectified power through the rectifier 20 is not just provided to the transformer 40, but also connected to the power control unit 30 to supply a rectified power in the rectifier 20 to the second side in accordance with a power control of the power controller 30.
However, there was a problem that if the voltage of an input power is lowered below 80V, the power controller 30 does not operate or the image display device turns off by the operations of an overload circuit (not shown). Even the power voltage goes back to normal, a user have to re-enter the power key to operate the image display device.